Electromagnetic stainless steel having excellent machinability

ABSTRACT

An electromagnetic stainless steel in which corrosion resistance and the magnetic property inherent in said steel is not decreased and machinability is improved by incorporating therein machinability improving alloy elements. These elements are selected from the group consisting of Pb, Ca and Te and are added to an electromagnetic stainless steel comprising up to 0.05 percent C, 11 to 20 percent Cr and a conventional amount of magnetic property improving alloy elements such as silicon and aluminum which are incidentally contained in said steel or an electromagnetic stainless steel comprising up to 0.08 percent C, 10 to 20 percent Cr, up to 5 percent Mo and a conventional amount of magnetic property improving alloy elements such as silicon and aluminium which are incidentally contained in said steel.

United States Patent Kato et a1. 5] Dec. 9, 1975 [5 ELECTROMAGNETIC STAINLESS STEEL 3.634974 1/1972 Ito 75/126 M HAVING EXCELLENT MACHINABILITY 3.645.722 2/1972 Aulenbach 75/126 M 3,723.103 7/1970 Km 75/123 F Assignee:

Inventors: Tetsuo Kato; lsao Sekio, both of Nagoya, Japan Daido Seiko Kabushiki Kaisha, Nagoya, Japan Sept. 18, 1972 [21] Appl. No.: 289,883

[44] Published under the Trial Voluntary Protest Program on January 28, 1975 as document no. B 289,883.

{52] [1.8. CI. 75/124; 75/123 F; 75/126 R; 75/126 M; 75/126 Q [51] Int. CL. C22C 38/22 [58] Field of Search 75/126 M, 128 P, 126 R, 75/123 F, 126 Q 156] References Cited UNITED STATES PATENTS 2,121,001 1/1938 Arness 75/126 M 2,255,895 9/1941 Bessemer l 75/128 P 2,615,367 10/1971 Tanczyn 75/126 M 3,607,246 9/1971 Kalita l l 75/124 Primary ExaminerL. Dewayne Rutledge Assistant Examiner-Arthur J. Steiner Attorney, Agent, or FirmWenderoth, Lind & Ponack [57] ABSTRACT An electromagnetic stainless steel in which corrosion resistance and the magnetic property inherent in said steel is not decreased and machinability is improved by incorporating therein machinability improving alloy elements. These elements are selected from the group consisting of Pb, Ca and Te and are added to an electromagnetic stainless steel comprising up to 0.05 percent C. l 1 to 20 percent Cr and a conventional amount of magnetic property improving alloy elements such as silicon and aluminum which are incidentally contained in said steel or an electromagnetic stainless steel comprising up to 0.08 percent C, 10 to 20 percent Cr, up to 5 percent Mo and a conventional amount of magnetic property improving alloy elements such as silicon and aluminium which are inci dentally contained in said steel.

4 Claims, 18 Drawing Figures U.S. Patent Dec. 9, 1975 Sheet 1 of 6 3,925,063

-m m F 5 w w w m m w 0 1 1 A EE mmwEm oz m wzw 5 w w m w w m o :3: HES @258 JEGZEQ CUTTING SPEED (m/min) CUTTING SPEED (m/min) m m o m 5 D E E w a w G 2 1.. N m m w F m m w m w m m o 1 33 mwwEm QZEEIm O o) z .m m o m 5 .l D E B D. m m G l H w U w C m w o w m w o 4 3x538 02:50 JEQZEQ US. Patent Dec. 9, 1975 Sheet 2 of6 3,925,063

FIG. 3

FLANK WEAR \N W|DTH(mm) i 2 i4 1'o 2 03 040606050 CUTTING TIMES IN MINUTES FIG. 4

STEEL NO. I STEEL NO. 2

STEEL 4 STEEL NO. 5

U.S. Patent Dec. 9, 1975 Sheet of6 3,925,063

FIG. 108

FIG. IOA

W NUMBERS OF S NU MBE RS OF STEELS 0 A IV mumOm mZotwOu STEELS FIG.

I0 so |OO CUTTING TIMES MINUTES) ELECTROMAGNETIC STAINLESS STEEL HAVING EXCELLENT MACHINABILITY DETAILED EXPLANATION OF THE INVENTION 2 cium and tellurium in a suitable amount. Also the inventors have found that it is preferable to use as a base steel a chromium-type electromagnetic stainless steel comprising up to 0.05 percent of carbon, 1 l to 20 per- 5 cent of chromium and a suitable amount of magnetic This invention relates to an electromagnetic stainless property improving alloy elements such as silicon and steel having improved machinability without reduced aluminium which are incidentally contained in said corrosion resistance, mechanical strength and magsteel. Still further, the inventors have found that it is netic property inherent in an anticorrosive, soft magpreferable to use lead in an amount of 0.03 to 0.40 pernetic material, especially a chromium-type electromagl cent, calcium in an anount of 0.001 to 0.0l percent and netic stainless steel by incorporating at least one matellurium in an amount of 0.01 to 0.30 percent as the chinability improving alloy elements selected from the machinability improving alloy elements. group consisting of lead, calcium and tellurium in said The reasons why carbon, chromium and the magmaterialnetic property improving alloy elements are as defined Presently, it is known in the art to use great quantities l in the base steel and why the machinability improving of certain electromagnetic stainless steels such as a 13 elements are as defined in this invention are explained Cr-type steel and an 18 Cr-type steel as electromagas follows. netic materials inacorrosive-environment and for elec- 1. It is desirable to include a very small amount of tromagnetic valves, solenoid relays and electromagcarbon in the base steel to maintain the corrosion resisnetic clutches. Also, it is known in the art that such 13 20 tance and magnetic property of the base steel but the Cr-type and 18 Cr-type stainless steels are improved carbon content of the base steel is defined to 0.05 perwith respect to their magnetic property when a convencent or less on the basis of the considerable progress in tional amount, for example, 1 to 6 percent of silicon refining techniques for molten steels. and a conventional amount, for example, 0.5 to 5 per- '2. Chromium does not give satisfactory corrosion recent of aluminum are incidentally contained in said sistance to the base steel when it is used in an amount steels. below ll percent and also the base steel has reduced in Generally, it is desirable to include a very small workability suchasforgeability and rollability, and beamount of carbon in the electromagnetic steels to comes expensive if chromium is present in the steel in maintain their magnetic property but in such a case, an amount of above 20 percent. they are increased in softness and glutinosity and as a 3. Silicon and aluminium surely achieve the desirable result they have decreased machinability which is magnetic property of the base steel if incidentally conjudged on the basis of the cutting force and the tooltained in the base steel. failure. Also, the electromagnetic stainless steels have 4. Lead does not give an excellent machinability imdecreased hot workability and cold workability when proving effect to the base steel if it is used in an amount they have increased amounts of silicon and aluminium. of below 0.03 percent but the base steel has reduced Further, it has been proposed to incorporate titanium, mechanical and magnetic properties if lead is used in zirconium, niobium and tantalum with the chromiuman amount of above 0.40 percent. type electromagnetic stainless steels because the stabi- 5. Calcium acts to improve the hot workability of the lization of the ferrite phase is effective for the improvebase steel so that the life of a cutting tool operated at ment of the magnetic property of such stainless steels high speed for cutting is greatly increased if calcium is but other alloy elements are not taken into considerused in an amount of above 0.001 percent but the base ation. Such being the case, it can be said that few studsteel has reduced in machinability and mechanical ies of electromagnetic stainless steels have so far been property due to an increase of oxide inclusions if calmade with respect to the improvement of their machincium is used in an amount of above 0.009 percent. ability. 6. Tellurium acts to improve the machinability of the We, the inventors have investigated certain electrobase steel if it is used in an amount above 0.0] percent magnetic stainless steels with a view to improving their but the base steel does not have further improved mamachinability without reducing corrosion resistance, chinability and affected mechanical and magnetic mechanical strength and the magnetic property inherproperties if tellurium is used in an amount of above ent in certain electromagnetic stainless steels and have 0.30 percent. found that a certain chromium-type electromagnetic Now, this invention is illustrated in reference to the stainless steel has improved in machinability when said claimed steels in comparison with the base steels as steel contains at least one machinability improving elelisted in the following Table l. ment selected from the group consisting of lead, cal- Table 1 Nos. of Steels C Si Mn Cr Al Pb Te Ca 13 1" 0.015 0.65 0.10 13.19 c1 2 0.016 0.64 0.11 13.20 0.14 type 3 0.022 0.88 0.22 13.56 0.21 0.14 0.10 Stain- 6 0.021 0.83 0.21 l3.6l 0.22 0.03 lESS 7 0.020 0.89 0.22 13.60 0.20 0.30 0.003 steels 8 0.019 0.76 0.25 13.54 0.22 0.38

13 4" 0.020 0.60 0.20 17.60 Cr- 5 0.019 0.59 0.21 17.59 0.11 0.004 type 9 0.020 0.59 0.20 17.60 0.19 0.19 Stain- 10 0.018 0.55 0.19 19.01 0.17 0.08 0.001 less H 0.017 0.54 0.20 19.00 0.18 0.009

Table l-continued Nos. of Steels C Si Mn Cr AP Ph Te Ca steels l2 0.023 0.61 0.]8 17.83 0.23 0.08 0.15 0.007

Note: The mark indicates the magnetic property improving alloy elements incidentally contained in the base steels and the mark indicates the base steels.

It will be understood from the chemical compositions of the steels listed in the Table 1 that the steel Nos. 2,

that the base steels produced long and flowing state as 10 shown in FIG. 4 when they are cut at a cutting speed of 3, 6, 7 and 8 and the steels Nos. 5, 9, 10, 11 and 12 are 100 m/min. 13 Cr-type and 18 Cr-type electromagnetic stainless Next, the test samples having a size of 60 mm in disteels of th1s invention respectively and the steel No. 1 ameter as mentioned above were cut out into ring-like and 4 are the 13 Crand 18 Cr-type base steels. All the test pieces having a size of 45 mm in outside diameter, steels were melted and cast, and then the cast steels 15 33 mm in inside diameter and 10 mm in thickness. The were sub ected to hot forging and/or hot rolling to form ring-like test pieces were tested for their magnetic test samples having a size of 60 mm in diameter and property by a direct electric current. The test results then the test samples were annealed in a vacuum at are given in the following Table 2.

Table 2 Nos. of Test Coercive Residual Saturation Pieces which Max. permeability force magnetism value correspond to 43, (G) HC (e) Br (G) an (0) Nos. of Steels 13 1* 4,300 1.5 11,600 14,200 Cr- 2 4,100 1.0 11,100 14,100 type 3 4,300 0.15 9,900 13,400 Stain- 6 3,780 1.4 9,300 13,400 less 7 4,570 1.3 10,400 13,400 Steel 8 4,040 1.4 8,000 13,200

18 4* 4,800 1.4 10,500 13,500 Cr- 4,500 1.4 10,600 13,400 type 9 4,880 1.4 8,600 13,400 Stain 10 3,330 1.6 0,900 13,300 less 11 3,130 1.7 7,400 13,400 Steel 12 4,740 1.5 8,500 13,400

850C for 4 hours. The annealed test samples were tested for cutting. The test results are shown in FIG. IA, FIG. l-B, FIG. 2-A and FIG. 2-B. FIGS. l-A and -B indicate the relationship between the cutting speed (m/min.) and the principal cutting force against the tool-chip contact plane. Also, FIGS. 2-A and -B indicate the relationship between the cutting speed (m/min.) and the shearing stress on the shear plane. As is obvious from the FIGS. l-A to 2-D, the low carbon 13 Cror 18 Cr-type electromagnetic stainless steels containing at least one element from the group consisting of Pb, Ca and Te in accordance with this invention are greatly improved with respect to the principal cutting force against the tool-chip contact plane, feeding force and shearing stress on the shear plane in comparison with the base steels.

Also, it is noted that such an improvement tends to decrease as the cutting speed increases.

Also, the above-mentioned annealed test samples were tested for flank wear of a K l0-cutting tool (W- Co-Ti-Ta cemented carbide tipped tool) when they are cut at a cutting speed of 2 to 100 m/min., a cut depth of 1.0 mm and a feed of 0.12 mm/rev. The test results are shown by curves as shown in FIG. 3 indicating the relationship between the flank wear of the K lO-cutting tool and the cutting time. It is obvious from the curves shown in the FIG. 3 that the electromagnetic stainless steels of this invention have improved machinability in comparison with the base steels. This proves that the life of the cutting tool is prolonged.

Further, the shapes of the chip were observed and it was found that the electromagnetic stainless steels of this invention produces small sheared chips and also [t is noted from the data as shown in the Table 2 that the magnetic properties of the electromagnetic stainless steels of this invention did not deteriorate relative to the magnetic properties inherent in the base steels when the base steels had added thereto an machinability improving alloy element (Pb, Ca or Te) in a suitable amount.

Also the test samples were tested for corrosion resistance by dipping them for 6 hours in a 65 percent boiling nitric acid. The test results are shown in FIGS. 5 and 6 and it was found that the corrosion resistance and mechanical properties of the steels of this invention are equal to those of the base steels.

Also, the inventors have investigated other electromagnetic stainless steels with a view to improving the machinability, corrosion resistance and magnetic prop erty without causing deterioration of the mechanical properties inherent in the electromagnetic stainless steels and have found that a certain chromium-type electromagnetic stainless steel can be given improved machinability by incorporating therein at least one machinability improving alloy elements selected from the group consisting of lead, calcium and tellurium in a suitable amount. With the inventors have found that it is preferable to use as a base steel 21 chromiumtype electromagnetic stainless steel comprising as the principal alloy elements up to 0.08 percent of carbon, 10 to 20 percent of chromium, up to 5 percent of molybdenum and a suitable amount of magnetic property improving alloy elements such as silicon and aluminium which are incidentally contained in the base alloy. Still further, the inventors have found that it is preferable to use lead in an amount of 0.03 to 0.30 percent, calcium 5 in an amount of 0.002 to 0.02 percent and tellurium in an amount of 0.01 to 0.20 percent as the machinability improving alloy elements.

The reasons why the principal alloy elements and 6 high speed cutting is greatly increased if calcium is used in an amount of above 0.002 percent but the base steel has deteriorated machinability and mechanical properties due to the increase of oxide inclusions if calcium is magnetic property improving alloy elements are in- 5 used in an amount of above 0.02 percent. cluded in the base steel and also why the machinability vii. Tellurium acts to improve the machinability of improving alloy elements are included in this invention the base steel if it is used in an amount of above 0.0l are explained as follows. percent, but the base steel has deteriorated magnetic 1. It is desirable to include a very small amount of carproperties, workability and mechanical properties if bon in the base steel when the corrosion resistance and 10 tellurium is used in an amount of above 0.20 percent. magnetic property of the base steel are to be improved Now this invention is illustrated in reference to the but the carbon content of the base steel is defined as claimed steels in comparison with the base steels as being 0.08 percent or less for taking into consideration listed in the following Table 3.

Table 3 Nos. of Steels C Si Mn Cr Mo Al Pb Te Ca A" 0.021 0.90 0.33 13.30 0.26 13 B" 0.020 0.92 0.27 13.43 0.20 0.11 c 0.022 0.93 0.20 13.43 0.52 0.22 0.09 0.03 Cr- D 0.017 0.93 0.29 13.22 1.32 0.27 0.12 type E 0.011 1.08 0.20 l3.l8 2.96 0.19 0.006 P 0.022 0.94 0.27 13.12 1.04 0.17 0.13 0.10 0.009 Staino 0.018 0.92 0.27 13.93 0.10 0.21 0.01 0.017 less H 0.018 0.87 0.34 13.00 3.01 0.24 19 1 0.019 096 0.30 14.54 3.50 0.22 0.01s Steels .l 0016 0.90 0.29 13.22 4.01 0.|8 0.10 0.015 K 0024 0.88 0.35 12.03 4.75 0.11 a 0.002

18 R" 0.027 0.86 0.36 13.04 0.22 Cr s 0.013 0.90 0.48 17.96 0.47 0.19 0 14 type 'r 0.019 0.99 0.26 18.01 1.00 0.16 0.06 Stain- U 0.010 0.94 0.33 18. 11 2.37 0.24 0.10 0.003 less v 0.020 0.95 0.33 10.15 3.47 0.17 0.09 0.08 0.010 Steels w 0.017 0.91 0.31 19.43 3.51 0.14 0.07 0.10 0.014

Note: The marl: indicates the magnetic property improving alloy elements incidentally contained in the base steels and the mark indicates the base steels.

the melting conditions of the base steel.

ii. The lower limit of the chromium content is defined as being 10% in order to maintain or improve corrosion resistance inherent in the base steel and the upper limit of the chromium content is defined as being 20 percent to achieve good hot workability such as forgability and rollability and to keep the price of the base steel down.

iii. Molybdenum improves the magnetic property of the base steel in an amount up to 3 percent but it is preferable to use molybdenum in an amount up to percent for improving the corrosion resistance of the base steel.

iv. Silicon and aluminium act to improve the magnetic and oxidation properties of the chromium-type stainless steels comprising up to 0.08 percent of carbon and to percent of chromium and therefore such a magnetic property improving element is incorporated as an incidental element in such a chromium-type stainless steel in a conventional amount. The improvement is achieved without adversely influencing the improvement in machinability due to the inclusion of Ca, Pb and Te. it is noted that titanium, vanadium, niobium, tantalum, zirconium and tungsten can be used similarly to silicon and aluminum for improving the magnetic properties of the chromium-type stainless steel.

v. Lead does not produce an excellent effect on the machinability of the base steel if it is used in an amount of below 0.03 percent but the base steel has deteriorated magnetic properties, workability and mechanical properties if lead is used in an amount of above 0.30 percent.

vi. Calcium acts to improve the hot workability of the base steel so that the life of the cutting tool operated at It will be understood from the chemical compositions of the steels listed in the Table 3 that the steels C, D, E, F, G, H, l, J and K are 13 Cr-type stainless steels of this invention and the steels A and B are 13 Cr-type base steels. Also, the steels S, T, U, V and W are 18 Cr-type stainless steels of this invention and the steel R is l8 Crtype base steel. All the steels were melted and cast, and then the cast steels were subjected to hot forging and- /or hot rolling to form test samples having a size of mm in diameter and then the test samples were annealed at 850C for 4 hours. The annealed test samples were tested for their corrosion resistance against brine, nitric acid and acetic acid by measuring the weight loss of the samples during tests in which they were continuously sprayed with the brine for 96 hours, or dipped in the boiling percent nitric acid or 20 percent acetic acid for 6 hours. [t was found from the test results that the steels C to K have improved corrosion resistance in comparison with the steels A and B. For example, the steel No. E has the highest corrosion resistance against attack by the brine and the steels C, D and B have a greatly reduced weight loss as compared with the steels A and B when they are attacked with nitric acid. Also the steel C was compared with the steel A as to resistance to attack by acetic acid and it was found that the weight loss of the steel C is less than 50 percent of the weight loss of the steel A. Still further, it was found from the test results that the weight loss of the steels S, T, U, V and W is greatly decreased independently of the presence of the corrosion resistance improving alloy elements as the amount of molybdenum increases.

The test results are given in the following Table 4.

Table 4 Weight loss in gjrn /hr. [dipped in the boiling 65% Weight loss in glm lhr. (dipped in the boiling 20% The test samples having a size of 60 mm in diameter as mentioned above were cut into ring-like test pieces having a size of 45 mm outside diameter, 33 mm inside diameter and 10 mm thickness. The ringlike test pieces were tested for their magnetic properties. The test re sults are indicated in FIGS. 7-A and 7-13.

It is noted from the FIG. 7-A that the maximum permeability of the steels C and D of this invention is con siderably higher than that of the base steels A and B, and also that the steels C and D have slightly reduced coercive force and saturation values. Also it is noted from the FIG. 7-B that the magnetic properties of steels F, G, H, l, J and K of this invention are not deteriorated.

This proves that the molybdenum-containing 13 Crtype stainless steels have improved magnetic properties.

Also, the annealed test samples were tested for machinability by being cut by using a S3-cutting tool (W- Ti-Co-C type cemented carbide tipped tool) at a 1.2 mm depth of cut and a feed of 0.15 mm/rev. The test results are shown in FIGS. 8-A and 8-8. FIGS. 8-A and 8-13 indicate the relationship between the cutting speed ranging from 100 to 150 m/min. and the cutting resistance (kg) and it is obvious that the low carbon 13 Crtype stainless steels C, D and E containing at least one element from the group consisting of Pb, Ca and Te in accordance with this invention are greatly improved with respect to the principal cutting force against the tool-chip contact plane and the feeding force in an addition to an improvement of shear stress on the shear plane as compared with the base steel A at any cutting speed as indicated. Also it was found that the abrasion of cutting tools is not increased but is improved by the presnece of molybdenum in the 13 Cr-type stainless steels. Further the chips were observed after the annealed test samples were cut. For example, the steel C of this invention produced the chips as shown in FIG. 9-A and the steel A produces the chips as shown in FIG. 9-13. This proved that the steel C has improved machinability because of containing Pb and Te as the machinability improving alloy elements.

Also the test samples were cut into ring-like test pieces having the same size as the size of the test pieces of the 13 Cr-type stainless steels and then they were tested for their magnetic properties. The test results are indicated in FIG. l-A and -B. It was found that the steels S, T, U, V and W of this invention have a coercive force of below 2.0 oersteds and the maximum permeability of 3,000 to 3,500. This proves that a machinability improving alloy when present in a small amount have no effect on the magnetic property of the 18 Cr type stainless steels.

Further the annealed test samples were tested for flank wear of a cutting tool having the Trade Mark SKI-l4 by cutting them at a cutting speed of 60 m/min., the cut depth of 1.0 mm and a feed of 0.084 mm/rev. while using a cutting fluid having the Trade Mark NH-30. The test results are shown by the curves as shown in FIG. 11 which indicates the relationship between the flank wear and the cutting time. It is obvious that the steels S to W of this invention have improved flank wear in comparison with the steel R.

Still further, some test samples were prepared by using the steels A, D, F, I, .I, R, U and W. The test samples were tested for their mechanical properties. It was observed that the steels D, F, I, .I, U and W tend to increase in tensile strength but decrease in elongation as compared with the steels A and R and it should be noted that such results depend upon the presence of molybdenum but not upon the machinability improving alloy elements contained in the steels.

The test results are shown in FIG. 12.

What we claim is that:

1. An electromagnetic stainless steel having improved machinability consisting essentially of up to 0.05% carbon, 1 I to 20 percent chromium, silicon as a magnetic property improving alloy element in an amount up to 6 percent, aluminium as a magnetic property improving alloy element in an amount up to 5 percent, at least one machinability improving alloy element selected from the group consisting of 0.03 to 0.40 percent lead, 0.001 to 0.009 percent calcium and 0.01 to 0.30 percent tellurium, and the balance iron.

2. An electromagnetic stainless steel as claimed in claim 1, wherein the machinability improving alloy element is selected from the group consisting of 0.03 to 0.40 percent lead and 0.001 to 0.009 percent calcium.

3. An electromagnetic stainless steel having improved machinability consisting essentially of up to 0.08 percent carbon, 10 to 20 percent chromium, up to 5 percent molybdenum, silicon as a conventional magnetic property improving alloy element in an amount up to 6 percent, aluminium as a magnetic property improving alloy element in an amount up to 5 percent, at least one machinability improving alloy element se lected from the group consisting of 0.03 to 0.30 percent lead, 0.002 to 0.02 percent calcium and 0.01 to 0.20 percent tellurium, and the balance iron. ment is selected from the group consisting of 0.03 to 4. An electromagnetic stainless steel as claimed in 0.30 percent lead and 0.002 to 0.02 percent calcium. claim 2, wherein the machinability improving alloy ele- 

1. AN ELECTROMAGNETIC STAINLESS STEEL HAVING IMPROVED MACHINABILITY CONSISTING ESSENTIALLY OF UP TO 0.05% CARBON, 11 TO 20 PERCENT CHROMIUM, SILICON AS A MAGNETIC PROPERTY IMPROVING ALLOY ELEMENT IN AN AMOUNT UP TO 6 PERCENT, ALUMINUM AS A MAGNETIC PROPERTY IMPROVING ALLOY ELEMENT IN AN AMOUNT UP TO 5 PERCENT, AT LEAST ONE MACHINABILITY IMPROVING ALLOY ELEMENT SELECTED FROM THE GROUP CONSISTING OF 0.03 TO 0.40 PERCENT LEAD, 0.001 TO 0.009 PERCENT CALCIUM AND 0.01 TO 0.03 PERCENT TELLURIUM, AND THE BALANCE IRON.
 2. An electromagnetic stainless steel as claimed in claim 1, wherein the machinability improving alloy element is selected from the group consisting of 0.03 to 0.40 percent lead and 0.001 to 0.009 percent calcium.
 3. An electromagnetic stainless steel having improved machinability consisting essentially of up to 0.08 percent carbon, 10 to 20 percent chromium, up to 5 percent molybdenum, silicon as a conventional magnetic property improving alloy element in an amount up to 6 percent, aluminium as a magnetic property improving alloy element in an amount up to 5 percent, at least one machinability improving alloy element selected from the group consisting of 0.03 to 0.30 percent lead, 0.002 to 0.02 percent calcium and 0.01 to 0.20 percent tellurium, and the balance iron.
 4. An electromagnetic stainless steel as claimed in claim 2, wherein the machinability improving alloy element is selected from the group consisting of 0.03 to 0.30 percent lead and 0.002 to 0.02 percent calcium. 